How many other states could McGovern have won?

[Sumner 1868]

I'm guessing Rhode Island, at the very least.

[DS0816]

Rhode Island has voted the same as Hawaii since the latter's first vote in 1960. (They have, ever since, carried Republican only with the 49-state re-elections of a 1972 Richard Nixon and a 1984 Ronald Reagan.) So, if we're thinking of Nixon not re-elected with 49 but closer to 40 states, the takeaways, in addition to Rhode Island would have started with Hawaii as well. And I would guess Minnesota. (I haven't look at state percentage margins, from that election, in quite a while.)

[🐒Gods of Prosperity🔱🐲💸]

Rhode Island has voted the same as Hawaii since the latter's first vote in 1960. (They have, ever since, carried Republican only with the 49-state re-elections of a 1972 Richard Nixon and a 1984 Ronald Reagan.) So, if we're thinking of Nixon not re-elected with 49 but closer to 40 states, the takeaways, in addition to Rhode Island would have started with Hawaii as well. And I would guess Minnesota. (I haven't look at state percentage margins, from that election, in quite a while.)

Hawaii didn't shine to McGovern at all for some reason. Maybe they felt out there in the middle of the Pacific that Nixon's foreign policy was keeping them secure.

MN was the closest loss for McGovern, followed by RI and then SD.  If he managed to cut the vote gap in half by winning about 43% of the vote, he could get something like:

 

[DS0816]

One thing to keep in mind is this: Richard Nixon, with re-election in 1972, was the first from his Republican party to carry all 11 states of the Old Confederacy with percentage margins about his national number.

Eight years earlier, in 1964, Lyndon Johnson became the first from his Democratic party to carry all the states we recognize today as "Blue Firewall" states, with their margins, above his national number.

To ask what other states a landslided George McGovern may have also carried is a change in the race. So, if we were to lower it as much as 40 for Nixon and 10 for McGovern, I'd say that Hawaii would have been in McGovern's column. So, too, with Rhode Island. I would say that all 32 states Richard Nixon carried in 1968 would remain Republican holds in 1972 (as was actually the case). And Nixon would have won the Republican pickups out of the south (which were in the 1968 column for American independent George Wallace) as well as a pickup of [1968 Democratic] Texas. Anything McGovern would have carried, with a maximum of ten, would have been outside the Old Confederacy states (as was the case with a 1948 Thomas Dewey and a 1988 Michael Dukakis).

[Podgy the Bear]

Even if McGovern were to have come up to 43% (which was Humphrey's percentage in 1968), he would have a lot of trouble to pick up states other than those that have been mentioned (Rhode Island and South Dakota likely, Minnesota probably, Wisconsin and Oregon possibly). 

I doubt that even with 43%, McGovern could have picked up states that Humphrey won (including New York, Pennsylvania, and Michigan).

With 41 electoral votes in 1972, New York going for Nixon by a wide margin was probably his biggest success.  It was his largest plurality (his percentage--just under 60%-- was higher than that of California, and he almost won New York City!).  Theodore White discussed it in his Making of the President series.  At that time, the conservatives (Buckley wing) and the liberals (Rockefeller wing) united for a big victory there.  Plus, the Democrats at the state level were effectively nonfunctional in the early 1970s.   

[SingingAnalyst]

Probably none. Despite the popularity of McGovern among college students, the working white noncollege young stayed with Nixon. The nation saw McGovern as too radical, that's it. Best case maybe RI, MN, SD, but that's a stretch.